US5527018A - Filter unit and apparatus for desludging salt baths - Google Patents

Filter unit and apparatus for desludging salt baths Download PDF

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Publication number
US5527018A
US5527018A US08/342,581 US34258194A US5527018A US 5527018 A US5527018 A US 5527018A US 34258194 A US34258194 A US 34258194A US 5527018 A US5527018 A US 5527018A
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US
United States
Prior art keywords
filter
riser tube
filter unit
bath
desludging
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US08/342,581
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English (en)
Inventor
George Wahl
Matthias Kremer
Tokuo Sato
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Durferrit GmbH Thermotechnik
Houghton Durferrit GmbH
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Durferrit GmbH Thermotechnik
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Filing date
Publication date
Priority claimed from DE4400755A external-priority patent/DE4400755A1/de
Application filed by Durferrit GmbH Thermotechnik filed Critical Durferrit GmbH Thermotechnik
Assigned to LEYBOLD DURFERRIT GMBH reassignment LEYBOLD DURFERRIT GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KREMER, MATTHIAS, SATO, TOKUO, WAHL, GEORG
Assigned to DURFERRIT GMBH THERMOTECHNIK reassignment DURFERRIT GMBH THERMOTECHNIK ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: LEYBOLD DURFERRIT GMBH
Application granted granted Critical
Publication of US5527018A publication Critical patent/US5527018A/en
Assigned to HOUGHTON DURFERRIT GMBH reassignment HOUGHTON DURFERRIT GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DURFERRIT GMBH THERMOTECHNIK
Assigned to DURFERRIT GMBH reassignment DURFERRIT GMBH CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: DURFERRIT GMBH THERMOTECHNIK
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/10—Filter screens essentially made of metal
    • B01D39/12—Filter screens essentially made of metal of wire gauze; of knitted wire; of expanded metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • B01D29/117—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for outward flow filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/39—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with hollow discs side by side on, or around, one or more tubes, e.g. of the leaf type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
    • B01D29/90—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for feeding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
    • B01D29/94—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for discharging the filter cake, e.g. chutes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/26—Filters with built-in pumps filters provided with a pump mounted in or on the casing

Definitions

  • the invention relates to a filter unit and apparatus for desludging salt baths, which is at least partially flooded by the salt bath and is in working connection with the upper end of a riser tube, while the bath fluid that is to be desludged is forced by means of a compressed-air stream through the riser toward the filter unit.
  • Salt baths are widely used, for example for the hardening or nitriding of metal materials, especially iron materials.
  • Such salt baths consist predominantly of carbonates and cyanates of the alkali metals, and to some extent alkali cyanides are also contained in them.
  • Such molten salts are normally operated at a temperature of 560° to 600° C.
  • sludge During the treatment of components made from ferrous materials these baths form sludge in varying degrees, due to the fact that adherent steel particles, such as turning chips or grinding dusts, collect on the bottom of the treatment vessel or remain suspended in finely divided form. Likewise, the treatment of scaly or unworked surfaces (castings or forgings) leads to contamination of the bath. Lastly, sludge content is also formed by the fact that loading aids, such as baskets or frames, flake off nitride particles after many uses, which remain in the bath. The "sludge” thus formed consists mainly of iron nitride and iron oxide.
  • salt baths such as quenching baths on a hydroxide basis
  • salt baths of this kind must also be cleaned up.
  • DE-OS 29 11 222 discloses an apparatus for the continuous desludging of salt baths, which consists of a filter unit, a pump immersed in the salt bath, and a riser tube.
  • the filter unit is in this case disposed outside of the salt bath.
  • Woven screens of iron wire have the disadvantage that the iron material is severely attacked--embrittled for example--by the salt bath itself and also by the substances contained in the filter sludge, so that after a few hours of operation the screen tears or breaks open or develops holes, with the result that the retained filter sludge pours through into the cleaned bath and abruptly renders it unusable.
  • DAS 27 31 167 Also known (DAS 27 31 167) is the use of inorganic molded materials, especially glass wool or rock wool, for the cleaning of molten salt baths, especially for the removal of harmful suspended substances and settled sludge in baths for the structural treatment of ferrous materials.
  • glass wool or rock wool filters however, have the disadvantage among others that they are hard to dispose of when contaminated, so that they are impractical for reasons of cost.
  • a filtering means with an electrogalvanically built-up filter medium is known (DGM 92 00 734.1), wherein the filter medium is made from nickel or a nickel alloy and has a thickness of 0.1 to 0.2 mm.
  • This known filter medium in the form of a pressure screening fabric, is suitable only as a multi-stage separating system, a band filter for example, which is connected to the output of hydrocyclones.
  • the present invention is addressed to the problem of creating not only a filter unit for desludging salt baths, whose useful life is substantially longer than that of the conventional filter units, but also the apparatus corresponding to this filter unit, which can be made especially cheaply and operates with a high degree of efficiency.
  • the filter fabric enveloped by a filter basket is made from a filter cloth made of a woven wire of a nonferrous metal, preferably of an alloy on an aluminum, nickel or titanium basis.
  • all alloys are suitable for the filter fabric in which any metal, with the exception of iron, makes up the greatest single component.
  • the apparatus necessary for the filter unit is formed from a frame shaped into a funnel toward the bottom of the salt bath, the pointed bottom end of which is provided with an opening which can be closed with a stopper rod.
  • FIG. 1 is a perspective view of a filter unit and according to the invention, together with the salt bath tank,
  • FIG. 2 is a perspective view of the filter unit itself according to FIG. 1,
  • FIG. 3 is a diagrammatic representation of a desludging procedure through 34 charges, the iron content of the charge being given in %,
  • FIG. 4 is a perspective view of an alternative embodiment of a filter unit together with the pump unit and the salt bath tank, and
  • FIGS. 5, 6, 7 are perspective views of the pump unit, the filter unit and the stopper, respectively, in the embodiment according to FIG. 4.
  • the molten salt 1, which is situated in a vat 2, is continuously pumped through a riser tube 3 into the filter unit 9 where a sheet metal spreader 7 is cupped over the upper end of the riser tube 3.
  • the molten salt 1 is driven by means of the air stream rising in the salt.
  • the air is delivered through a compressed air feed line 4, while the aspirating tube 5 draws the sludge from the lowermost point in the vat 2.
  • the filter is held by an abutment 8 and is easily replaceable.
  • Beneath the surface of the salt bath the riser tube 3 is provided with a number of holes 6 which serve to relieve pressure if the filter 9 or the upper end of the riser tube 3 becomes clogged.
  • the holes 6 have a diameter, for example, of 2 to 16 mm, depending on the riser tube diameter, and they are located below the bath surface.
  • the molten stream driven upward by the air stream strikes against the inside surface of the bell-shaped spreader 7 and is steered by the latter into the pack of woven aluminum wire 10. After being cleaned the molten stream seeping through the filter pack 10 flows back into the salt melt.
  • FIG. 2 shows a separate filter unit which includes a box-like frame 11, the filter pack 10 composed of aluminum wire cloth surrounded by the frame 11, a hanger loop 12 and a trough-like recess 13 to accommodate the riser tube 3.
  • the filter unit 9 can be raised easily at any time, from the bath or from the holding frame 8.
  • FIG. 3 shows in a diagram the result of a series of tests, in which the salt bath was cleaned by means of a filter unit made of a pure aluminum wire cloth.
  • the curve shows that the content of iron particle sludge has remained extraordinarily low even after the treatment of 34 charges, and up to about the 25th charge has the very low level of 0.011% Fe, and even after that another phase falls to a still better level (0.009% Fe), until at the end it rises again to a level that is slightly above the starting level.
  • the woven filter pack should have between 200 and 800 meshes/cm 2 .
  • the mesh size used in this experiment was 400 meshes per square centimeter.
  • the filter pack of aluminum wire cloth 10 is held by a frame 14 which in turn is supported by means of the hooks 15 and 16 on the edge 17 of the salt bath vat 2.
  • the frame 14 encompasses with its two side parts 14a and 14b the mattress-like filter pack 10 and also has a downwardly pointing sheet-metal funnel 18 which is provided at its bottom end with an opening 19 which can be closed with a stopper rod 20 provided for this purpose with a conical stopper 21.
  • the side part 14b is equipped with a collector box 22 through which the fluid that is pumped through the riser tube 23 can flow transversely into the filter pack 10 through the side part 14b.
  • the sheet-metal funnel 18 provided below the filter pack serves to catch the filter sludge which sinks down from the filter pack.
  • the collected sludge can be let out by raising the stopper rod 20 above the opening 19 at the tapered bottom end of the sheet-metal funnel 18.
  • the pump (ejector pump) formed by the riser tube 23 and the compressed air feed tube 34 serves to pump the fluid out of vat 2 into the collector box 22.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Filtration Of Liquid (AREA)
  • Filtering Materials (AREA)
  • Polarising Elements (AREA)
  • Cosmetics (AREA)
US08/342,581 1994-01-13 1994-11-21 Filter unit and apparatus for desludging salt baths Expired - Lifetime US5527018A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4400755.8 1994-01-13
DE4400755A DE4400755A1 (de) 1993-01-26 1994-01-13 Filtereinheit und Vorrichtung zum Entschlammen von Salzbädern

Publications (1)

Publication Number Publication Date
US5527018A true US5527018A (en) 1996-06-18

Family

ID=6507811

Family Applications (1)

Application Number Title Priority Date Filing Date
US08/342,581 Expired - Lifetime US5527018A (en) 1994-01-13 1994-11-21 Filter unit and apparatus for desludging salt baths

Country Status (8)

Country Link
US (1) US5527018A (es)
EP (1) EP0663455B1 (es)
JP (1) JP3631789B2 (es)
AT (1) ATE186754T1 (es)
BR (1) BR9404469A (es)
CA (1) CA2136169C (es)
DK (1) DK0663455T3 (es)
ES (1) ES2138638T3 (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109173377A (zh) * 2018-09-27 2019-01-11 潍坊昌盛硝盐有限公司 一种便于更换的高温熔盐加工用过滤网
US11560113B2 (en) * 2021-01-06 2023-01-24 ZF Passive Safety Systems US Inc. Airbag module with airbag retainer filter layer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017115908B3 (de) * 2017-07-14 2018-07-12 Rhewum Gmbh Siebbelag zum Klassieren von trockenem oder nassem Siebgut sowie hierauf basierende Siebanwendungen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1004618A (en) * 1961-12-07 1965-09-15 Degussa A process for nitriding ferrous metals
DE2731167A1 (de) * 1977-07-09 1979-01-18 Degussa Verfahren und vorrichtung zum reinigen von salzschmelzbaedern
US4448611A (en) * 1982-04-23 1984-05-15 Centre Stephanois De Recherches Mecaniques Hydromecanique Et Frottement Process for improving the corrosion resistance of ferrous metal parts
US4714549A (en) * 1985-04-29 1987-12-22 Vincenzo Di Leo Filtering case for separating a liquid from a solid, in particular for dehydrating slurries from industrial processes
DE9200734U1 (de) * 1992-01-23 1992-05-07 Gebr. Schmid GmbH & Co, 7290 Freudenstadt Vorrichtung zur Aufbereitung einer partikelbeladenen in einem Prozess anfallenden Flüssigkeit
JPH05230525A (ja) * 1992-02-18 1993-09-07 Parker Netsushiyori Kogyo Kk スラッジ除去装置を一体化した溶融塩槽

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2911222A1 (de) * 1979-03-22 1980-11-06 Degussa Verfahren und vorrichtung zum entschlammen von salzbaedern
DE3836939C1 (es) * 1988-10-29 1989-06-15 Degussa Ag, 6000 Frankfurt, De
DE4337374C2 (de) * 1992-11-09 1998-06-10 Honda Motor Co Ltd Vorrichtung zum Entschlammen einer Salzschmelze

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1004618A (en) * 1961-12-07 1965-09-15 Degussa A process for nitriding ferrous metals
DE2731167A1 (de) * 1977-07-09 1979-01-18 Degussa Verfahren und vorrichtung zum reinigen von salzschmelzbaedern
US4448611A (en) * 1982-04-23 1984-05-15 Centre Stephanois De Recherches Mecaniques Hydromecanique Et Frottement Process for improving the corrosion resistance of ferrous metal parts
US4714549A (en) * 1985-04-29 1987-12-22 Vincenzo Di Leo Filtering case for separating a liquid from a solid, in particular for dehydrating slurries from industrial processes
DE9200734U1 (de) * 1992-01-23 1992-05-07 Gebr. Schmid GmbH & Co, 7290 Freudenstadt Vorrichtung zur Aufbereitung einer partikelbeladenen in einem Prozess anfallenden Flüssigkeit
JPH05230525A (ja) * 1992-02-18 1993-09-07 Parker Netsushiyori Kogyo Kk スラッジ除去装置を一体化した溶融塩槽

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
Aluminium Taschenbuch, Aluminuim Verlag GmbH D sseldorf, 1974, p. 319. *
Aluminium Taschenbuch, Aluminuim-Verlag GmbH Dusseldorf, 1974, p. 319.
Volk, Nickel und Nickellegierungen, Springer Verlag Berlin, Heidelberg, New York 1970 p. 357. *
Volk, Nickel und Nickellegierungen, Springer-Verlag Berlin, Heidelberg, New York 1970 p. 357.
Zwicker, Titan und Titanlegierungen, Springer Verlag Berlin, Heidelberg, New York 1974 pp. 539 561. *
Zwicker, Titan und Titanlegierungen, Springer-Verlag Berlin, Heidelberg, New York 1974 pp. 539-561.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109173377A (zh) * 2018-09-27 2019-01-11 潍坊昌盛硝盐有限公司 一种便于更换的高温熔盐加工用过滤网
US11560113B2 (en) * 2021-01-06 2023-01-24 ZF Passive Safety Systems US Inc. Airbag module with airbag retainer filter layer

Also Published As

Publication number Publication date
CA2136169A1 (en) 1995-07-14
EP0663455A1 (de) 1995-07-19
EP0663455B1 (de) 1999-11-17
CA2136169C (en) 2005-05-24
JP3631789B2 (ja) 2005-03-23
DK0663455T3 (da) 2000-05-15
BR9404469A (pt) 1995-10-17
ES2138638T3 (es) 2000-01-16
ATE186754T1 (de) 1999-12-15
JPH07222905A (ja) 1995-08-22

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